If you let the opposing team get the escort to within 20 meters of the extract then you should lose.

I know for a fact there aren't turrets at the end of the Security escort mission.

That screenshot is from the Resistance one, and I never got that far on it yet (have only played as Security, and they never got the guy even remotely close to their objective). It also doesn't give a clear enough view to say whether those are fixed indestructible turrets or player-built ones - from the way they're positioned, though, I'm guessing they're permanent and you're right.

From the look of it though, you can line up decent shots at the VIP without needing to go into the turrets' firing arcs, so it's more like 5 - 10m from the objective before you have trouble.

Without having seen the area in question properly, I can't say 100% whether it's truly fair or not, but I think if those ARE super-turrets, and if they kick in early enough that you really can't get anywhere once the VIP is in that area, then they probably should remove at least the one on the left in that picture (the other one has a much more restrictive firing arc)

They are not player built.

But that means the END is when they are ABOUT to get to those turrets. Eh?

Oh, fair enough. Spawn turrets are made to protect against spawncamping, but since that's not a spawn anymore, they SHOULD be removed.